This invention relates to an air distribution unit for delivering conditioned air into an area or space, and more particularly relates to a control for maintaining the flow of conditioned air into the area at a minimum predetermined rate irrespective of the temperature requirements of the space.
The utilization of air conditioning air distribution units to supply conditioned air from a central source thereof to offices, schoolrooms, and other similar spaces or areas in multi-room buildings has become increasingly prevalent. Such distribution units are typically located in the ceiling of the rooms or areas being conditioned, or on the floor thereof adjacent the windows. The flow of conditioned air from the units is generally regulated by operation of suitable damper means controlled by a thermostat sensing the temperature of the space being conditioned. Thus, as the temperature of the space deviates to a greater degree from a predetermined set point, a greater quantity of conditioned air is discharged into the area. Conversely, when the temperature in the space being conditioned approaches the set point, the quantity of conditioned air discharged thereinto is reduced.
An air distribution unit of the type suitable for installation in a ceiling that has met with widespread commercial success is disclosed in U.S. Pat. No. 3,143,292, issued Aug. 4, 1964, and assigned to the same assignee as the assignee hereof.
Many of the units of the type disclosed in the afore-cited patent have included means to substantially terminate the flow of conditioned air into the space when the temperature therein equals the desired set point. However, many modern building codes require that air distribution units maintain the flow of a minimum quantity of air into a space to insure adequate ventilation. Thus, an air distribution unit having the capability to substantially terminate the flow of conditioned air is not satisfactory in meeting the requirements of the above building codes.
The particular unit disclosed in the above-cited patent includes a control member having a fixed orifice to insure a minimum quantity of air flow into the space being conditioned. However, it has been found that the fixed orifice, due to its relatively small size, can become clogged by dirt or other foreign bodies to thereby prevent the required minimum flow of conditioned air for ventilating purposes. The maintenance required to insure that the orifice remains unclogged is both time consuming and relatively expensive. It is further desirable to obtain the minimum flow of conditioned air from the unit without adversely affecting the aerodynamic characteristics of the unit.